0137033451 pp6

Copyright ©2011, 2006 by Pearson Education, Inc.publishing as Pearson [imprint]

Construction Methods and Management, 8th ed.S. W. Nunnally

Chapter 6

ROCK EXCAVATION



INTRODUCTION

• Rock Characteristics– Rock may be classified as igneous,

sedimentary, or metamorphic, according to its origin. Igneous rock formed when the Earth’s molten material cooled.

– Because of its origin, it is quite homogeneous and is therefore the most difficult type of rock to excavate.



INTRODUCTION

• Rock Investigation– Relative hardness is measured on Moh’s

scale from 1 (talc) to 10 (diamond). – As a rule, any rock that can be scratched

by a knife blade (hardness about 5) can be easily excavated by ripping or other mechanical methods.



INTRODUCTION

FIGURE 6-1. Schematic representation of seismic refraction test.



INTRODUCTION

FIGURE 6-2. Graph of refraction test data.



INTRODUCTION

FIGURE 6-3. Graph of refraction test data, Example 6-1.



INTRODUCTION

• Rock-Handling Systems– The process of rock moving may be

considered in four phases: • Loosening• Loading• Hauling• Compacting



INTRODUCTION

Table 6-1. Principal rock-handling systems



INTRODUCTION

• Tunneling– Tunneling in rock is a specialized form of

rock excavation that has traditionally been accomplished by drilling and blasting.

– Recently, however, tunneling machines or mechanical moles equipped with multiple cutter heads and capable of excavating to full tunnel diameter have come into increasing use.



INTRODUCTION

FIGURE 6-4. Large tunneling machine. (Courtesy of The Robbins Company)



INTRODUCTION

FIGURE 6-5. Hydraulic jumbo. (Courtesy of Atlas Copco)



DRILLING

• Drilling Equipment– Common types of drilling equipment include

percussion drills, rotary drills, and rotary-percussion drills.

Table 6-2. Typical characteristics of rock drilling equipment



DRILLING

FIGURE 6-6. Hydraulic track drill. (Courtesy of Atlas Copco)



DRILLING

FIGURE 6-7. Rotary blast hole drill. (Courtesy of Ingersoll-Rand Company)



DRILLING

FIGURE 6-8. Downhole drill mounted on a rotary drill. (Courtesy of Ingersoll-Rand Company)



DRILLING

FIGURE 6-9. Drill penetration versus air pressure.



DRILLING

Table 6-3. Representative drilling rates (carbide bit)



DRILLING

• Drill Bits and Steel

FIGURE 6-10. Major types of rock drill bits.



DRILLING

• Drilling Patterns and Rock Yield

Table 6-4. Typical drill hole spacing (rectangular pattern) [ft (m)]



DRILLING

FIGURE 6-11. Principal drilling patterns.



BLASTING

• Explosives– The principal explosives used for rock

excavation include dynamite, ammonium nitrate, ammonium nitrate in fuel oil (ANFO), and slurries.



BLASTING

• Electric Blasting Circuits

FIGURE 6-12. Types of electric blasting circuits.



BLASTING

Table 6-5. Representative current requirements for firing electric blasting caps



BLASTING

Table 6-6. Representative resistance of electric blasting caps



BLASTING

Table 6-7. Resistance of solid copper wire



BLASTING

FIGURE 6-13. Circuit for Example 6-3.



BLASTING

• Nonelectric Blasting Circuits

• Controlled and Secondary Blasting

• Blasting Safety

FIGURE 6-14. Hydraulic demolition hammer. (Courtesy of Allied Construction Products, Inc.)



ROCK RIPPING

• Employment of Rippers– Rippers have been utilized since ancient

times to break up hard soils. – However, only since the advent of the

heavy-duty tractor-mounted ripper has it become feasible to rip rock.



ROCK RIPPING

FIGURE 6-15. Heavy-duty crawler-mounted ripper. (Reprinted Courtesy of Caterpillar Inc.)



ROCK RIPPING

• Ripping Equipment• Ripper Production• Considerations in

Ripping

FIGURE 6-16. Adjustable parallelogram ripper.



ROCK RIPPING

FIGURE 6-17. Ripper performance vs. seismic velocity. (Reprinted Courtesy of Caterpillar Inc.)

0137033451 pp6

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